Few of us will know what it means to have a genuine legacy, something that really needs to be cared for, protected, regarded. Performers such as Robert De Niro and Sylvester Stallone must know that issue all too well, each having created a coterie of legendary characters in their long careers.

So in the new film "Grudge Match," which plays with the imagery and iconography of two of their best-known creations, are we all sharing a wink and a laugh as the points of reference somehow add something deeper to our understanding? Or are they diverting our attention while reaching into our pockets in a cheap hustle?

Maybe both? Directed by Peter Segal, from a script credited to Tim Kelleher and Rodney Rothman, the film sets Stallone and De Niro against each other as onetime rivals in the boxing ring who never had a third and deciding bout. Stallone's Henry "Razor" Sharp has lived a quiet workman's life out of the spotlight at a steel mill in the 30 years since, while De Niro's Billy "The Kid" McDonnen has milked his fame for every last drop of money and attention. Circumstances bring them together one more time for a rematch that starts as something of a joke and cash-grab (sound familiar?) and winds up meaning more to the both of them.

The movie is betting that audiences will get a kick out of seeing Rocky Balboa and Jake "Raging Bull" LaMotta duking it out at last. The play on actors and their screen personas brings to mind Marlon Brando in "The Freshman," where without the winking regard for the actor's role in "The Godfather" the film would scarcely exist. Or as in the recent "The Family," where a character played by De Niro watches De Niro's film "Goodfellas."

"Grudge Match" never settles on the movie it wants to be, wavering uncertainly between a jokey old-guys comedy and something more dramatic and heartfelt. It never lands the combination of being both. Alan Arkin and Kevin Hart are funny in supporting roles but pitch the story too broadly, particularly in contrast to Jon Bernthal's storyline as De Niro's long-lost son.

At times it seems as if De Niro and Stallone are performing in different movies. De Niro chuckles his way through the role with the same deprecating self-regard as many of his recent comedies. Stallone has a few unexpectedly strong dramatic scenes opposite Kim Basinger as the woman who got between Razor and the Kid, showing the genuine soulfulness that has often made Stallone a compelling performer even in his worst movies.

Building to a fight that is a bit more sluggish than slugfest, "Grudge Match" can never figure out just what it's trying to prove. Pleasant but underwhelming, it feels like something that belongs on the undercard, never reaching the heights of a main event. The characters of Rocky Balboa and Jake LaMotta still exist elsewhere, their respective legacies unsullied. But such iconic characters, and this includes Stallone and De Niro, deserve better.